...Do you leave it plugged in at all times or just when you need to diagnose a problem?
I myself have one that has an on/off button. I did at one time have
a ScanGauge plugged into my OBD2, but I noticed one evening a
faint 'glow' coming from inside the car...it was the ScanGauge...
so the OBD2 port was still live ! Finding and seeing that explained
the occasional struggle to start the car some mornings.
So...I would recommend that you unplug yours when you are not
using the car. Ok, it's a bit of a fiddle unclipping the underdash
panel each time..but I found on eBay a short OBD2 extension
lead so that I can place/fit the ELM unit up to the left of the
steering column where there is that wee 'shelf' space. The
cable slips easily into the gap between the column and panel.
It can be useful to have the EML unit working when using the
car as the Torque/Dashboard Apps can display
RPM, boost,
oil pressure, oil temp, mpg, and lots of other stuff. What you see
displayed is down to your choice, as is the size and style of each
item you want to display !
(Your screen is the limiting factor)It really is neat...
PROVIDING you have your smartphone in a cradle
where you can see it
easily.....NOT in your hands or on your lap !
BUT..to be totally honest with everyone, the 'novelty' soon
wears off, and your full concentration returns to the pleasure
of driving rather than taking your eyes off the road to 'oggle'
the pretty coloured moving displays. Soon it will only take
your interest as and when you think something is amiss or
it takes your fancy to try to 'impress' your mates....LOL